Apparatus and method for making measurements in universal mobile telecommunications system user equipment

ABSTRACT

A method and apparatus for taking measurements in a mobile telecommunications system is disclosed, the system comprising a network of a plurality of cells and at least one user equipment device. The user equipment device scans frequency bands to generate measurement data for signals received from cells of the network; and when the signals received from cells of the network include more than one signal in a frequency band, measurement data is generated for more than one signal in the frequency band.

BACKGROUND

1. Technical Field

This application relates to UMTS (Universal Mobile TelecommunicationsSystem) in general, and to an apparatus and method for makingmeasurements in universal mobile telecommunications system userequipment.

2. Description of the Related Art

The approaches described in this section could be pursued, but are notnecessarily approaches that have been previously conceived or pursued.Therefore, unless otherwise indicated herein, the approaches describedin this section are not prior art to the claims in this application andare not admitted to be prior art by inclusion in this section.

In a typical cellular radio system, mobile user equipment (UE)communicates via a radio access radio network (RAN) to one or more corenetworks. User equipment (UE) comprises various types of equipment suchas mobile telephones (also known as cellular or cell phones), lap topswith wireless communication capability, personal digital assistants(PDAs) etc. These may be portable, hand held, pocket sized, installed ina vehicle etc and communicate voice and/or data signals with the radioaccess network.

The radio access network covers a geographical area divided into aplurality of cell areas. Each cell area is served by at least one basestation, which may be referred to as a Node B. Each cell is identifiedby a unique identifier which is broadcast in the cell. The base stationscommunicate at radio frequencies over an air interface with the UEswithin range of the base station. Several base stations may be connectedto a radio network controller (RNC) which controls various activities ofthe base stations. The radio network controllers are typically connectedto a core network.

UMTS is a third generation public land mobile telecommunication system.Various standardization bodies are known to publish and set standardsfor UMTS, each in their respective areas of competence. For instance,the 3GPP (Third Generation Partnership Project) has been known topublish and set standards for GSM (Global System for MobileCommunications) based UMTS, and the 3GPP2 (Third Generation PartnershipProject 2) has been known to publish and set standards for CDMA (CodeDivision Multiple Access) based UMTS. Within the scope of a particularstandardization body, specific partners publish and set standards intheir respective areas.

Consider a wireless mobile device, generally referred to as userequipment (UE), that complies with the 3GPP specifications for the UMTSprotocol. The 3GPP 25.331 specification, v.3.13.0, referred to herein asthe 25.331 specification, addresses the subject of the Radio ResourceControl (RRC) protocol specification. The 3GPP 25.304 specification,v.3.13.0, referred to herein as the 25.304 specification, addresses thesubject of UMTS User Equipment (UE) procedures in idle mode andprocedures for cell reselection in connected mode between the UMTSTerrestrial Radio Access Network (UTRAN) and the UE.

Such a UE undertakes frequent measurement procedures. Clause 8.4 of the25.331 standard and its sub-clauses and clause 14 and its sub-clausesrelate to the measurement procedures to be undertaken by the UE as doclause 5 and its sub-clauses of the 25.304 specification. Both the25.331 standard (and in particular clauses Clause 8.4 and itssub-clauses and clause 14 and its sub-clauses) and the 25.304 standard(and in particular clauses 5.2.3.1 and its sub-clauses) are incorporatedherein by reference.

In accordance with clause 5.2.3.1.1 of the 25.304 specification, the UEshall use one of the following two search procedures:

a) Initial Cell Selection

This procedure requires no prior knowledge of which RF channels are UTRAcarriers. The UE shall scan all RF channels in the UTRA bands accordingto its capabilities to find a suitable cell of the selected Public LandMobile Network (PLMN). On each carrier, the UE need only search for thestrongest cell. Once a suitable cell is found this cell shall beselected.

b) Stored Information Cell Selection

This procedure requires stored information of carrier frequencies andoptionally also information on cell parameters, e.g. scrambling codes,from previously received measurement control information elements. Oncethe UE has found a suitable cell for the selected network the UE shallselect it. If no suitable cell of the selected network is found, theInitial Cell Selection procedure shall be started.

However the initial cell procedure as set out in a) above requires thatthe UE only searches for the strongest cell for each carrier (i.e.frequency or frequency band). The UE then attempts to connect with theselected cell. If there is any problem with doing so, the UE then triesthe cell which had the next strongest signal at another frequency.However this may not in reality be the next strongest signal.

There are thus proposed strategies for User Equipment (UE) measurementprocedures, which are appropriate in idle mode and during cell selectionin connected mode. A number of such strategies are detailed below.

Other aspects and features of the present invention will become apparentto those ordinarily skilled in the art upon review of the followingdescription of specific embodiments of an apparatus and method forcarrying out User Equipment (UE) procedures in idle mode and proceduresfor cell reselection in connected mode.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way ofexample only, with reference to the attached drawings, in which:

FIG. 1 shows an overview of a network and UE device;

FIG. 2 is a flow diagram illustrating a first embodiment;

FIG. 3 is a flow diagram illustrating a second embodiment;

FIG. 4 is a flow diagram illustrating a third embodiment;

FIG. 5 is a flow diagram illustrating a fourth embodiment;

FIG. 6 is a block diagram illustrating an embodiment of a protocol stackapparatus provided with a RRC block, in accordance with the presentapplication;

FIG. 7 is a block diagram illustrating a mobile device, which can act asa UE and co-operate with the apparatus and methods of FIGS. 1 to 6.

The same reference numerals are used in different figures to denotesimilar elements.

DETAILED DESCRIPTION OF THE DRAWINGS

A method and apparatus for making measurements in mobiletelecommunications system user equipment is described. In the followingdescription, for the purposes of explanation, numerous specific detailsare set forth in order to provide a thorough understanding of thepresent invention. It will be apparent, however, to one skilled in theart that the present invention may be practised without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring thepresent invention.

The needs identified in the foregoing Background, and other needs andobjects that will become apparent from the following description, areachieved by, in one aspect, a method for taking measurements in a mobiletelecommunications system, the system comprising a network of aplurality of cells and at least one user equipment device. The methodcomprises, at the user equipment device, scanning frequency bands togenerate measurement data for signals received from cells of thenetwork. When the signals received from cells of the network includemore than one signal in a frequency band, measurement data is generatedfor more than one signal in the frequency band.

In other aspects, the invention encompasses apparatus and acomputer-readable medium configured to carry out the foregoing steps. Inparticular, the method may be implemented in a mobile telecommunicationsdevice, with or without voice capabilities, or other electronic devicessuch as handheld or portable devices.

FIG. 1 shows an overview of a network and a UE device. Clearly inpractice there may be many UE devices operating with the network but,for the sake of simplicity, FIG. 1 only shows a single UE device. Forthe purposes of illustration, FIG. 1 also shows a network having a fewcomponents. It will be clear to a person skilled in the art that inpractice a network will include far more components than those shown.

FIG. 1 shows an overview of the radio access network 702 (UTRAN) used ina UMTS system. The network 702 as shown in FIG. 1 comprises three RadioNetwork Subsystems (RNS) 2. Each RNS has a Radio Network Controller(RNC) 4. Each RNS 2 has one or more Node B 6 which are similar infunction to a Base Transmitter Station of a GSM radio access network.User Equipment UE 700 may be mobile within the radio access network.Radio connections (indicated by the straight dotted lines in FIG. 1) areestablished between the UE and one or more of the Node Bs in the UTRAN.

The radio network controller controls the use and reliability of theradio resources within the RNS 2. Each RNC may also be connected to a 3Gmobile switching centre 10 (3G MSC) and a 3G serving GPRS support node12 (3G SGSN).

An RNC 4 controls one or more Node B's. An RNC plus its Node B'stogether make up an RNS 2. A Node B controls one or more cells. Eachcell is uniquely identified by a frequency and a primary scrambling code(primary CPICH in FDD, primary CCPCH in TDD).

Generally in UMTS a cell refers to a radio network object that can beuniquely identified by a UE from a cell identifier that is broadcastover geographical areas from a UTRAN access point. A UTRAN access pointis a conceptual point within the UTRAN performing radio transmission andreception. A UTRAN access point is associated with one specific celli.e., there exists one UTRAN access point for each cell. It is theUTRAN-side end point of a radio link. A single physical Node B 6 mayoperate as more than one cell since it may operate at multiplefrequencies and/or with multiple scrambling codes.

According to section 5.2.3.1.2 of the 25.304 standard, the cellselection criterion S is fulfilled when

Srxlev>0 and Squal>0 (for FDD Mode) or

Srxlev>0 (for TDD mode).

Squal is the Cell Selection quality value (dB) (applicable only for FDDcells) and Srxlev is the Cell Selection receive level value (dB)

Where

Srxlev=Qrxlevmeas−Qrxlevmin−Pcompensation

Squal=Qqualmeas−Qqualmin (FDD mode only) and

Qrxlevmeas is the Measured cell receive level value. This is receivedsignal, CPICH RSCP for FDD cells (dBm) and P-CCPCH RSCP for TDD cells(dBm).

Qrxlevmin is the Minimum required RX level in the cell (dBm)

Pcompensation is equal to max(UE_TXPWR_MAX_RACH−P_MAX, 0) (dB)

UE_TXPWR_MAX_RACH is the Maximum transmission power level an UE may usewhen accessing the cell on RACH (read in system information) (dBm)

P_MAX is the Maximum RF output power of the UE (dBm)

Qqualmeas is the Measured cell quality value i.e. the quality of thereceived signal expressed in CPICH Ec/N0 (dB) (applicable only for FDDcells).

Qqualmin is the Minimum required quality level in the cell (dB)(applicable only for FDD cells).

In the following description, the FDD mode will be considered. Howeverthe technique is also applicable in the TDD mode.

The UE occasionally carries out measurements of Srxlev and Squal. The UEscans all RF channels in the UTRA bands applicable for the device tofind a suitable cell of the selected network. The UE will typicallyperform these cell selection measurements on power-up or if trying tofind a cell when in a region with limited coverage (e.g. when in aremote area or a tunnel). Specifically the UE performs cell selectionmeasurements when it is currently not camped on a cell.

In a first embodiment, the UE is arranged during cell selection tosearch for more than one cell per frequency. This is illustrated in FIG.2 which is a flow chart illustrating the operation of a UE device. Atintervals the UE device carries out measurements, step 200. The UEcarries out measurements on all frequencies according to its capabilityfor all cells within range. In this embodiment, the UE is arranged togenerate measurement data for more than one signal in a frequency bandof interest. Thus, when signals received from cells of the networkinclude more than one signal in a frequency band of interest, the UEgenerates measurement data for each signal of the plurality of signalsin the frequency band.

The UE then determines whether the measurement data meets apredetermined criterion and stores the measurement data in an orderrelative to the meeting of the criterion. An example of a suitablecriterion is signal strength or Srxlev/Squal as discussed above.

Table 1 shows an example of the signal measurement results for a UE,with the strongest signals being shown at the top of the table and theweakest signals shown at the bottom. TABLE 1 C_(A) f₁ C_(D) f₁ C_(B) f₂C_(E) f₁ C_(F) f₃ C_(G) f₄ C_(H) f₃ C_(C) f₅ C_(I) f₆ C_(J) f₆where C_(A) indicates a signal from cell A and f₁ indicates a signal atfrequency f₁.

The UE uses these measurement results to identify the cell with thestrongest signal, step 202. In the example shown in table 1 this is thesignal from cell A at frequency f₁. The UE then checks whether theidentified cell at the identified frequency is suitable, step 204. Ifthe identified cell at the identified frequency is suitable, step 206,successful cell selection has occurred, step 208, and the UE continuesoperation. However the identified cell may not be suitable. For example,if the system information from a cell which informs the UE how toconnect to the cell has an error in it, then the cell is deemed to beunsuitable. For other examples, Clause 4.3 of the 25.304 standard setsout various basis on which a UE can decide if a cell is suitable.

However if the identified cell is not suitable at step 206, the UE thenidentifies the cell with the next strongest signal, step 210. The UEidentifies from the stored measurement data the cell with the nextstrongest signal at any frequency. In the example shown in table 1, thisis cell D at a frequency f₁, i.e., a different cell operating at thesame frequency as the previously identified cell. The UE then attemptsto connect with this identified cell at step 204 and if successful asuccessful cell connection with cell D at frequency f₁ is made.Otherwise the UE continues to identify cells with the next strongestsignal and to attempt to connect with these cells until a successfulconnection is made or connection to all potential cells has failed, inwhich case the UE returns a message to the user, for instance “emergencycalls only” or “no network coverage”. The UE then periodically repeatsthe search for a suitable cell.

Thus, rather than searching for just the strongest cell on each carrier,the UE may search for more than one cell per frequency. If the strongestcell is then found to be unavailable for any reason, the next best cellcan be used without the need for another cell search to be performed.This process is also applicable for scans where the UE carries outstored information cell selection (b of Clause 5.2.3.1.1 of the 25.304standard).

In an alternative embodiment, when an identified cell is deemedunsuitable, the scanning step is re-initiated with the omission from thescan of the cell or the frequency of the cell previously identified asthe cell which best meets a cell selection criterion.

FIG. 3 shows a second embodiment of the technique. In this embodiment,the UE carries out measurements to search for the strongest cell on eachcarrier required according to its capabilities, step 302. An example ofthe measurements made by a UE is shown in table 2, with the strongestsignals being shown at the top of the table and the weakest signalsshown at the bottom. TABLE 2 C_(A) f₁ C_(B) f₂ C_(F) f₃ C_(G) f₄ C_(C)f₅ C_(I) f₆

The UE then identifies the cell with the strongest signal, step 304. Forthe results shown in table 2, this is cell A at frequency f₁. The UEthen checks if this identified cell is suitable, step 306. If so, step308, a successful cell selection is made, step 410. However, if the cellis not suitable because it is barred for any reason (e.g. it is notsuitable owing to cell information (for example because the cell is noton the same public land mobile network (PLMN) as that selected by theUE)), step 312, and there are cells left to check, step 413, the UE thenidentifies the cell on the next strongest frequency, (frequency f₂, cellB), step 414, and checks if this is a suitable cell, step 406. If atstep 412 an identified cell is unsuitable for reasons owing to cellinformation (e.g. for being from a different PLMN), the UE excludes fromthe next measurement scan the previously identified cell (frequency f₁,cell A), step 316. The UE then initiates a new cell search, step 302.The UE may check the remaining identified cells for suitability (step313) before starting the new cell search. If a suitable cell is foundthen the new cell search is not required. The UE may optimise the newcell search to include only the frequency of the excluded cell(frequency f₁) since Cell A is known to be from the same PLMN as thatselected by the UE. This means that the UE only has to carry out a scanfor an alternative signal at the required frequency (f₁) rather thancarrying out a full scan at all frequencies. The results of this areshown in table 3. TABLE 3 C_(D) f₁ C_(B) f₂ C_(F) f₃ C_(G) f₄ C_(C) f₅C_(I) f₆

The UE has therefore excluded from the cell search scan any signals fromthe cell which was previously deemed unsuitable i.e cell A.

The UE then identifies from this second scan the cell with the strongestsignal, step 304. For the example results shown in table 3, this is cellD, frequency f₁. The UE then checks if this identified cell is suitable,step 306, and if so, step 308, a successful cell selection is made, step310. Otherwise the UE initiates another cell search with cell D excludedfrom the scan. This continues until a suitable cell is identified orconnection to all potential cells has failed, in which case the UEreturns a message to the user, for instance “emergency calls only” or“no network coverage”. The UE then periodically repeats the search for asuitable cell.

Thus, when the strongest cell on a particular frequency is unsuitable, anew cell search (initial cell selection or stored information cellselection) is started with the strongest cell specifically excluded fromthe search. This means that the next strongest cell on that frequencymay be returned by the cell search procedure.

FIG. 4 shows a third embodiment of the technique. In this embodiment,when no identified cells are deemed suitable by the UE, the scanningstep is re-initiated with certain frequencies omitted from the scan (forexample, frequencies which the UE is not allowed to use). In the case asdiscussed above, this means that the scan will omit the frequency of thecell previously identified as the cell which best meets a cell selectioncriterion. This means that the UE does not use up processing time togenerate measurement data for signals at a frequency that has alreadybeen deemed unsuitable. Where the system information for a cellindicates that the cell is unsuitable (for example SIB3 for a cellindicates that the cell is “barred” and the Information Element“Intra-frequency cell-reselection indicator” is set to “not allowed”),the UE is not allowed to select this cell or a cell on the samefrequency (see 25.304 clause 5.3.1.1). The approach described withreference to FIG. 4 means that the UE will not generate measurement datafor that frequency in a subsequent search and thus other (less strong)frequencies may be measured by the UE.

Thus, as shown in FIG. 4, at step 408, if a cell is deemed unsuitableand, at step 412 the cell is deemed unsuitable owing to cellinformation, (for instance, the cell is indicated as “barred” with theIE “Intra-frequency cell-reselection indicator” set to “not allowed”),then the UE omits that frequency from the next cell search, step 416, ifone is required. If there are cells which have yet to be checked, step413, then the UE continues the process with the next strongest cell,step 414. If all cells have been checked, and none found to be suitable,the UE starts a new cell search with any unsuitable frequencies omitted.This continues until a suitable cell is identified or connection to allpotential cells has failed, in which case the UE returns a message tothe user, for instance “emergency calls only” or “no network coverage”.The UE then periodically repeats the search for a suitable cell.

As an illustration, an example of the initial measurement resultsobtained at step 402 is shown in Table 4: TABLE 4 C_(D) f₁ C_(B) f₂C_(F) f₃ C_(G) f₄ C_(C) f₅ C_(I) f₆

For example, if cell B and cell G are found to be “barred” with the IE“Intra-frequency cell-reselection indicator” set to “not allowed”, andnone of the other cells are suitable, the UE will perform another cellsearch with frequencies f₂ and f₄ omitted. The results for the secondcell search may now include cells from frequencies not reportedpreviously due to constraints on the number of reported cells in themeasurement data, see Table 5. TABLE 5 C_(D) f₁ C_(F) f₃ C_(C) f₅ C_(I)f₆ C_(J) f₇ C_(K) f₈

The UE may scan all RF bands used by the network or the UE may scan onlythe RF bands known to be of interest to the UE (as indicated inpreviously stored information).

FIG. 5 is a flow diagram illustrating a combination of these approachesin which, at step 516, a further scan by the UE omits from the scan anypreviously identified cell(s) or the frequency of any previouslyidentified cell(s).

Referring to the drawings, FIG. 6 is a block diagram illustrating anembodiment of a UMTS protocol stack apparatus.

The RRC block 136 a sub layer of Layer 3 130 of a UMTS protocol stack100. The RRC 136 exists in the control plane only and provides aninformation transfer service to the non-access stratum NAS 134. The RRC136 is responsible for controlling the configuration of radio interfaceLayer 1 110 and Layer 2 120. When the UTRAN wishes to change the UEconfiguration it will issue a message to the UE containing a command toinvoke a specific RRC procedure. The RRC 136 layer of the UE decodesthis message and initiates the appropriate RRC procedure. Generally whenthe procedure has been completed (either successfully or not) then theRRC sends a response message to the UTRAN (via the lower layers)informing the UTRAN of the outcome. It should be noted that there are afew scenarios where the RRC will not issue a response message to theUTRAN and, in those cases the RRC need not and does not reply.

Turning now to FIG. 7, FIG. 7 is a block diagram illustrating a mobiledevice, which can act as a UE and co-operate with the apparatus andmethods of FIGS. 1 to 4, and which is an exemplary wirelesscommunication device. Mobile station 700 is preferably a two-waywireless communication device having at least voice and datacommunication capabilities. Mobile station 700 preferably has thecapability to communicate with other computer systems on the Internet.Depending on the exact functionality provided, the wireless device maybe referred to as a data messaging device, a two-way pager, a wirelesse-mail device, a cellular telephone with data messaging capabilities, awireless Internet appliance, or a data communication device, asexamples.

Where mobile station 700 is enabled for two-way communication, it willincorporate a communication subsystem 711, including both a receiver 712and a transmitter 714, as well as associated components such as one ormore, preferably embedded or internal, antenna elements 716 and 718,local oscillators (LOs) 713, and a processing module such as a digitalsignal processor (DSP) 720. As will be apparent to those skilled in thefield of communications, the particular design of the communicationsubsystem 711 will be dependent upon the communication network in whichthe device is intended to operate. For example, mobile station 700 mayinclude a communication subsystem 711 designed to operate within theMobitex™ mobile communication system, the DataTAC™ mobile communicationsystem, GPRS network, UMTS network, or EDGE network.

Network access requirements will also vary depending upon the type ofnetwork 702. For example, in the Mobitex and DataTAC networks, mobilestation 700 is registered on the network using a unique identificationnumber associated with each mobile station. In UMTS and GPRS networks,however, network access is associated with a subscriber or user ofmobile station 700. A GPRS mobile station therefore requires asubscriber identity module (SIM) card in order to operate on a GPRSnetwork. Without a valid SIM card, a GPRS mobile station will not befully functional. Local or non-network communication functions, as wellas legally required functions (if any) such as “911” emergency calling,may be available, but mobile station 700 will be unable to carry out anyother functions involving communications over the network 702. The SIMinterface 744 is normally similar to a card-slot into which a SIM cardcan be inserted and ejected like a diskette or PCMCIA card. The SIM cardcan have approximately 64 K of memory and hold many key configuration751, and other information 753 such as identification, and subscriberrelated information.

When required network registration or activation procedures have beencompleted, mobile station 700 may send and receive communication signalsover the network 702. Signals received by antenna 716 throughcommunication network 702 are input to receiver 712, which may performsuch common receiver functions as signal amplification, frequency downconversion, filtering, channel selection and the like, and in theexample system shown in FIG. 7, analog to digital (A/D) conversion. A/Dconversion of a received signal allows more complex communicationfunctions such as demodulation and decoding to be performed in the DSP720. In a similar manner, signals to be transmitted are processed,including modulation and encoding for example, by DSP 720 and input totransmitter 714 for digital to analog conversion, frequency upconversion, filtering, amplification and transmission over thecommunication network 702 via antenna 718. DSP 720 not only processescommunication signals, but also provides for receiver and transmittercontrol. For example, the gains applied to communication signals inreceiver 712 and transmitter 714 may be adaptively controlled throughautomatic gain control algorithms implemented in DSP 720.

Mobile station 700 preferably includes a microprocessor 738 whichcontrols the overall operation of the device. Communication functions,including at least data and voice communications, are performed throughcommunication subsystem 711. Microprocessor 738 also interacts withfurther device subsystems such as the display 722, flash memory 724,random access memory (RAM) 726, auxiliary input/output (I/O) subsystems728, serial port 730, keyboard 732, speaker 734, microphone 736, ashort-range communications subsystem 740 and any other device subsystemsgenerally designated as 742.

Some of the subsystems shown in FIG. 7 perform communication-relatedfunctions, whereas other subsystems may provide “resident” or on-devicefunctions. Notably, some subsystems, such as keyboard 732 and display722, for example, may be used for both communication-related functions,such as entering a text message for transmission over a communicationnetwork, and device-resident functions such as a calculator or tasklist.

Operating system software used by the microprocessor 738 is preferablystored in a persistent store such as flash memory 724, which may insteadbe a read-only memory (ROM) or similar storage element (not shown).Those skilled in the art will appreciate that the operating system,specific device applications, or parts thereof, may be temporarilyloaded into a volatile memory such as RAM 726. Received communicationsignals may also be stored in RAM 726.

As shown, flash memory 724 can be segregated into different areas forboth computer programs 758 and program data storage 750, 752, 754 and756. These different storage types indicate that each program canallocate a portion of flash memory 724 for their own data storagerequirements. Microprocessor 738, in addition to its operating systemfunctions, preferably enables execution of software applications on themobile station. A predetermined set of applications that control basicoperations, including at least data and voice communication applicationsfor example, will normally be installed on mobile station 700 duringmanufacturing. A preferred software application may be a personalinformation manager (PIM) application having the ability to organize andmanage data items relating to the user of the mobile station such as,but not limited to, e-mail, calendar events, voice mails, appointments,and task items. Naturally, one or more memory stores would be availableon the mobile station to facilitate storage of PIM data items. Such PIMapplication would preferably have the ability to send and receive dataitems, via the wireless network 702. In a preferred embodiment, the PIMdata items are seamlessly integrated, synchronized and updated, via thewireless network 702, with the mobile station user's corresponding dataitems stored or associated with a host computer system. Furtherapplications may also be loaded onto the mobile station 700 through thenetwork 702, an auxiliary I/O subsystem 728, serial port 730,short-range communications subsystem 740 or any other suitable subsystem742, and installed by a user in the RAM 726 or preferably a non-volatilestore (not shown) for execution by the microprocessor 738. Suchflexibility in application installation increases the functionality ofthe device and may provide enhanced on-device functions,communication-related functions, or both. For example, securecommunication applications may enable electronic commerce functions andother such financial transactions to be performed using the mobilestation 700.

In a data communication mode, a received signal such as a text messageor web page download will be processed by the communication subsystem711 and input to the microprocessor 738, which preferably furtherprocesses the received signal for output to the display 722, oralternatively to an auxiliary I/O device 728. A user of mobile station700 may also compose data items such as email messages for example,using the keyboard 732, which is preferably a complete alphanumerickeyboard or telephone-type keypad, in conjunction with the display 722and possibly an auxiliary I/O device 728. Such composed items may thenbe transmitted over a communication network through the communicationsubsystem 711.

For voice communications, overall operation of mobile station 700 issimilar, except that received signals would preferably be output to aspeaker 734 and signals for transmission would be generated by amicrophone 736. Alternative voice or audio I/O subsystems, such as avoice message recording subsystem, may also be implemented on mobilestation 700. Although voice or audio signal output is preferablyaccomplished primarily through the speaker 734, display 722 may also beused to provide an indication of the identity of a calling party, theduration of a voice call, or other voice call related information forexample.

Serial port 730 in FIG. 7, would normally be implemented in a personaldigital assistant (PDA)-type mobile station for which synchronizationwith a user's desktop computer (not shown) may be desirable, but is anoptional device component. Such a port 730 would enable a user to setpreferences through an external device or software application and wouldextend the capabilities of mobile station 700 by providing forinformation or software downloads to mobile station 700 other thanthrough a wireless communication network. The alternate download pathmay for example be used to load an encryption key onto the devicethrough a direct and thus reliable and trusted connection to therebyenable secure device communication.

Other communications subsystems 740, such as a short-rangecommunications subsystem, is a further optional component which mayprovide for communication between mobile station 700 and differentsystems or devices, which need not necessarily be similar devices. Forexample, the subsystem 740 may include an infrared device and associatedcircuits and components or a Bluetooth™ communication module to providefor communication with similarly enabled systems and devices.

Extensions and Alternatives

In the foregoing specification, the invention has been described withreference to specific embodiments thereof. It will, however, be evidentthat various modifications and changes may be made thereto withoutdeparting from the scope of the technique. The specification anddrawings are, accordingly, to be regarded in an illustrative rather thana restrictive sense.

It is to be noted that the methods as described have shown steps beingcarried out in a particular order. However, it would be clear to aperson skilled in the art that the order of some of the steps may beimmaterial with respect to the operation of the method. The ordering ofthe steps as described herein is not intended to be limiting.

It is also to be noted that where a method has been described it isintended that protection is also sought for a device arranged to carryout the method and where features have been claimed independently ofeach other these may be used together with other claimed features.

1. A method for taking measurements in a mobile telecommunicationssystem, the system comprising a network of a plurality of cells and atleast one user equipment device, the method comprising, at the userequipment device: scanning frequency bands to generate measurement datafor signals received from cells of the network; and identifying from themeasurement data the cell which best meets a cell selection criterion;determining whether the identified cell is suitable; and when theidentified cell is deemed unsuitable, re-initiating the scanning stepwith the omission from the scan of the cell previously identified as thecell which best meets a cell selection criterion.
 2. A method accordingto claim 1 further comprising when the identified cell is deemedunsuitable, re-initiating the scanning step with the omission from thescan of the frequency band of the cell previously identified as the cellwhich best meets a cell selection criterion.
 3. A method according toclaim 2 wherein an identified cell is deemed unsuitable when theidentified cell is barred with the an “Intra-frequency cell-reselectionindicator” set to “not allowed”.
 4. A method according to claim 1further comprising determining whether the measurement data meets apredetermined criterion and storing the measurement data in an orderrelative to the meeting of the criterion.
 5. A method according to claim1 further comprising determining whether the measurement data meets apredetermined criterion and storing the measurement data in an orderrelative to the meeting of the criterion; identifying from the storedmeasurement data the cell which best meets a cell selection criteria;determining whether the identified cell is suitable; and when theidentified cell is deemed unsuitable, identifying from the storedmeasurement data the cell with the next strongest signal at anyfrequency and determining whether the newly identified cell is suitable.6. Apparatus for taking measurements in a mobile telecommunicationssystem, the system comprising a network of a plurality of cells and atleast one user equipment device, the apparatus comprising a processorand memory, the apparatus being arranged to carry out the followingsteps: scanning frequency bands to generate measurement data for signalsreceived from cells of the network; and identifying from the generatedmeasurement data the cell which best meets a cell selection criterion;determining whether the identified cell is suitable; and when theidentified cell is deemed unsuitable, re-initiating the scanning stepwith the omission from the scan of the cell previously identified as thecell which best meets a cell selection criterion.
 7. Apparatus accordingto claim 6 wherein the apparatus is further arranged, when theidentified cell is deemed unsuitable, to re-initiate the scanning stepwith the omission from the scan of the frequency band of the cellpreviously identified as the cell which best meets a cell selectioncriterion.